The present invention relates to an air conditioning system for a vehicle including a primary compressor which is driven by a primary driving source including an engine and a secondary compressor driven by a secondary driving source including a motor.
Conventionally, there are known air conditioning systems for vehicle (hereinafter, referred simply to an “air conditioning system”) which use an engine driven compressor which uses a vehicular running engine as a driving source, an electric motor which is installed in an electric vehicle and a motor driven compressor which is used when the idling of an engine is stopped.
In recent years, there is an increasing tendency to drastically promote the conservation of environment and improvement in fuel economy, and in conjunction with this tendency, the number of vehicles having a stop-idling function tends to increase. In a vehicle having such a stop-idling function, when the vehicle is stopped while an air conditioning system is in use, the stop-idling function operates to stop the idling of the engine, and a compressor cannot operate in association with the stop of the engine. As a result, when the outside temperature is high or the sunlight is intense, the temperature of a passenger compartment of the vehicle increases, whereby there may occur a case where occupants feel uncomfortable. On the contrary, when the outside temperature is low, the dehumidifying capability is lowered to be short, and breath expelled from the occupants increases the humidity inside the passenger compartment, causing an inconvenient condition where windows are fogged.
Then, there is proposed an air conditioning system (for example, a patent literature No. 1) in which the engine is driven temporarily according to the temperature inside the passenger compartment to activate the compressor so as to adjust the temperature inside the passenger compartment to an appropriate level, and thereafter, the idling of the engine is stopped again.
In addition, in so-called mild hybrid vehicles, an air conditioning system is used in which a compressor is driven by an electric motor after the rotational speed of an engine becomes zero.
[Patent Literature No. 1]
JP-A-2000-179374 (pages 4 to 5, and FIGS. 3 and 5)
In these conventional air conditioning systems, however, even if the compressor is activated, a required cooling capability cannot be provided by the air conditioning system immediately after the activation of the system. As a result, the air conditioning is carried out only by a blower until the required cooling capability is provided by the air conditioning system. Consequently, since the temperature within the passenger compartment increases until then, there is caused a problem that the uncomfortableness cannot be eliminated within the passenger compartment.